Copy the convergence data file to a file called ``convPCCG.dat'' for
preconditioned conjugate gradients. Plot the convergence
( 
as a function of
iteration number) of convSD.dat, convLM.dat, convCG.dat and
convPCCG.dat all on the same graph to see the improvements you
have made!
Have this final plot ready to show the grader to get credit for this
assignment.